>>2047627no shit sherlock. But that is under very specific conditions only and very very quickly goes complete trainwreck.
Long story short, im not looking to be bored with retard takes itt:
They don't because it offers relatively weak corrosion protection compared to. paint. You can get that by just painting clear over it as it's the etch primer that makes the paint a very durable solution that offers good protection.
Idk why but /n/ is just always very bad when it comes to material science and other engineering topics even when its just trivial knowledge.